UC Santa Cruz

Many secondarily aquatic vertebrates, mammals, birds, and non-avian reptiles converged in behavioral, physiological, and morphological adaptations to utilize the aquatic environment. This dissertation aims to expand in our understanding of the adaptations of vertebrates that can move between land and water as part of their natural history. Garter snakes are excellent models for studying a semi-aquatic existence as they navigate both terrestrial and aquatic landscapes to refuge and forage. In Chapter 1, I thoroughly reviewed the literature to identify behavioral, physiological, and morphological adaptations in snakes for utilizing the aquatic environment. Chapter 2 investigates how ontogenetic changes in diving physiology and behavior including voluntary apnea and bradycardia to provide insight into significant dietary shifts in two closely related semi-aquatic garter snake species with different lifestyles. In Chapter 3, I examined aquatic foraging comparing aquatic prey capture in shallow and deep water in aquatic specialist Thamnophis eques obscurus, and terrestrial-aquatic generalist T. marcianus. Finally, Chapter 4 introduces a novel behavior in garter snakes where a narial bubble is used to extend time underwater in various contexts and interact with the exercise response. Collectively, my dissertation aims to better understand what it takes for garter snakes to exist on the terrestrial to aquatic interface.